Historically, wood has been the preferred material for athletic floors for indoor athletic venues such as gymnasiums, handball courts and the like. The structure of such flooring systems can be generally described as comprising; a bottom base, typically of concrete, a middle layer of structures referred to generally as the substructures, and the top surface which is the wood flooring. This invention relates to substructures for such flooring systems.
As the sophistication of athletics has grown, so has the development of the art and science of designing substructures for athletic floors. The substructures of athletic floors contribute significantly to the physical properties of the finished athletic floor. The athletic flooring industry has adopted a method for measuring both point elasticity and area elasticity of athletic floor constructions in terms of such factors as force attenuation, standard deformation, deformation trough, rolling load, and ball rebound, as percentages of established norms. United States Sports Labs. conducts tests to measure these properties of sports floors and to use the data taken to rate the floors. One such test that is widely accepted in the sports floor industry is the DIN 18032, Part II, test, (DIN). A DIN certification is given to floors that achieve satisfactory scores in the above described tests. The standards for DIN resting are set out in a paper titled DIN 18032 Part 2 (March 1991) as translated from the German, by Hans J. Kolitzus 1ST/USSL April 1992.
Acquiring certification under the DIN 18032 Part 2 requirements involves a series of tests and measurements done by a certified tester, under specified conditions, using specified methods and equipment.
For each of the categories of tests a specified number of measurements are taken and the results computed and averaged. The average result for each category of test must then meet the requirements for DIN certification in that category.
Force Attenuation is a measure of the force reduction achieved by a test floor as a percent of the force reduction achieved by a standardized rigid floor (steel over cement on compacted earth). The DIN test involves a dropped test weight acting through a spring loaded force transfer instrument. The force reduction is computed as a percent as; (1-Fmax test/Fmax stand.).times.100. For certification that value must be a minimum of 58%.
Standard Deformation is a measure of the vertical displacement of a test floor in response the impact of a dropped weight, measured at the location of the dropped weight on the test floor. Standard deformation is measured in millimeters and is computed by a formula that contains correction factors. For DIN certification, the computed standard deformation must be between 3.0 mm. minimum, and 5.0 mm. maximum.
Deformation Trough is a measure of vertical displacement of a test floor at 500 mm. from the location of impact of a draped weight. Deformation trough is computed as a percentage of the displacement of the floor at the location of impact. A maximum percentage of 5% is permitted for DIN certification.
Rolling Load is a measure of the effects of a weighted test wheel which is rolled over defined strips on the test floor a prescribed number of times (300 passes). The test floor is then cut up and examined. For DIN certification, no damage to the floor or its substructure can be found and any remaining impressions must be less than 0.5 mm.
Ball Rebound is a measure of the rebound of a standardized basketball dropped from a set height on a test floor and is computed as a percentage of the rebound of the basketball from a rigid floor. For DIN certification, the percentage must be a minimum of 90%.
The DIN test contains other measures such as, Sliding Coefficient, which are concerned with properties other than those significantly influenced by the flooring system of this invention.
Many of the substructures in use in the past do not yield an athletic floor that will perform at a level that will earn a DIN certification. As a result there has been a flurry of creative activity in the athletic flooring industry wherein many of the competitors have developed sophisticated and often more expensive substructures for athletic floors in order to achieve a desirable DIN certification.
As a result of this creative activity, many of the old reliable substructures that have shown their merit over the decades, have been abandoned. This invention relates to creative and unobvious improvements in such old reliable substructures which configure them so as to achieve a DIN certification.